Abstract

We propose time-division based color electroholography with a one-chip RGB Light Emitting Diode (LED) and a low-priced synchronizing controller. In electroholography, although color reconstruction methods via time-division have already been proposed, the methods require an LCD with a high refresh rate and output signals from the LCD for synchronizing the RGB reference lights such as laser sources, which consequently increase the development cost. Instead of using such an LCD, the proposed method is capable of using a general LCD panel with a normal refresh rate of 60 Hz. In addition, the LCD panel used in the proposed method does not require the output signals from the LCD. Instead, we generated synchronized signals using an external controller developed by a low-priced one-chip microprocessor, and, use a one-chip RGB LED instead of lasers as the RGB reference lights. The one-chip LED allows us to decrease the development cost and to facilitate optical-axis alignment. Using this method, we observed a multi-color 3D reconstructed movie at a frame rate of 20 Hz.

Timing chart of the time-division color reconstruction. The upper figure is the switching signal from PC to PIC. The middle chart is the display timing of CGH on the LCD. The bottom chart is the synchronized signal for the LED generated by the PIC.

Optical color reconstruction using the proposed method. (a) and (b) are an original color object and the color reconstruction without the collimator (the collimator and objective lenses) and the switch-off time, respectively. (c) is introduced the collimator and the switch-off time to improve blurring and remove unwanted reconstructed objects.

(a) is an original multi-color 3D movie, and (b) to (e) are the snapshot of the color reconstructed movie, respectively. This is an animation scene whereby the color phase of the character “Color” is changing and the color circle is rotating (
Media 1).